PHP's type juggling, does it work with object's __toString() magic method?

[Lord Yggdrasill]

Well in PHP, the below code defines number as string types but when you use plus, minus, multiply or other algorithmic operators they are converted to the corresponding number types:

$byte = "5";
$double = "6.4";
$sum = $byte + $double;
$product = $byte * $double;
echo $sum;
echo $product;
// produces 11.4 and then 32. 

Since PHP object has a magic method __toString(), I wonder if similar effect can be achieved with the following approach:

class Integer{
   private $value;

   public function($value){
      $this->value = (int)$value;
   }

   public function __toString(){
      return (string)$this->value;
   }
}

class Double{
   private $value;
   private $precision;
   
   public function __construct($value, $precision = ""){
      if(!empty($precision)) $value = (int)($value * pow(10, $precision)) / pow(10, $precision);
      $this->value = $value;
      $this->precision = $precision;
   }

   public function __toString(){
      return (string)$this->value;
   }
}

$byte = new Integer(5);
$double = new Double(6.4);
$sum = $byte + $double;
$product = $byte * $double;
echo $sum;
echo $product; 

Will the code above produce the same result? Or will it generate a syntax error/exception? Just curious.

[Weedpacket]

Will the code above produce the same result? Or will it generate a syntax error/exception? Just curious.

Have you tried it?

[traq]

Have you tried it?

Bonus question: why does $sum end up holding the value 2?


**********
[edit]

You could do it this way
(but please, please, don't)

<?php

// your code . . .

$sum = ((string)$byte) + ((string)$double);
$product = ((string)$byte) * ((string)$double);

[Lord Yggdrasill]

Bonus question: why does $sum end up holding the value 2?

Is this what you got after trying out the code? Weird, thought it'd either throw an exception or work normally lol.

[Weedpacket]

An example of PHP's automatic type conversion is the addition operator '+'. If either operand is a float, then both operands are evaluated as floats, and the result will be a float. Otherwise, the operands will be interpreted as integers, and the result will also be an integer.

language.types.type-juggling

Caution: The behaviour of converting to integer is undefined for [objects]. Do not rely on any observed behaviour, as it can change without notice.

language.types.integer.php#language.types.integer.casting

[Lord Yggdrasill]

Thats too bad, I hope someday PHP just implements a __toPrimitive() method, which can be not only string, but also int, float, boolean or even null.

[traq]

What you need to be doing instead is adding some math methods to you objects, or referencing the values directly:

$sum = $byte->theValue() + $double->theValue();
// etc. 

[Lord Yggdrasill]

What you need to be doing instead is adding some math methods to you objects, or referencing the values directly:

$sum = $byte->theValue() + $double->theValue();
// etc. 

I do have a Math class with a group of static methods to do these, but I was wondering if there were easier ways. Anyway nvm, it is just an experience I am conducting, PHP clearly aint like ruby in which everything is an object so some techniques do not work.

[NogDog]

I suppose that if you had the __toString() method return a numeric string, you could do something (kind of ugly) like:

$total = $someNumber + (string)$someObject; 

But that seems a rather obfuscating thing to do -- not something I'd care to run into when maintaining that code a year later, even if I didn't have to prepend the (string) part. Much easier to read would be:

$total = $someNumber + $someObject->descriptiveVariableName; 

Your mileage may vary, of course.

[traq]

Bonus question: why does $sum end up holding the value 2?

Is this what you got after trying out the code? Weird, thought it'd either throw an exception or work normally lol.

Did you try it out yourself?
See if you can figure out why it gets that answer.